RetroCade MegaWing

The Open Source RetroCade MegaWing provides all of the audio hardware needed to make sweet retro music in one convenient and easy to connect circuit board. It snaps into the Papilio Pro and gives it the necessary hardware resources to communicate with the outside world. Continue reading for more information about each hardware section of the RetroCade MegaWing.

2 – ¼” Stereo Audio Jacks with 18 bit Delta Sigma DAC

MIDI – In, Out, Through

uSD Card for MOD, MIDI, YM, SID, and config files

MicroJoystick – 4 directions, Select

2x16 LCD Display

16 Analog inputs for sliders and knobs

16 Digital inputs for switches and peripherals

MegaWing MIDI

The Midi section of the RetroCade MegaWing implements three MIDI jacks; MIDI IN, MIDI OUT, and MIDI THROUGH. MIDI In is used to connect MIDI instruments such as a MIDI Keyboard, MIDI control board, or MIDI sequencer to the RetroCade synth to send MIDI notes and Control Changes that tell the RetroCade what audio to output. MIDI Through is connected to the MIDI In port and passes everything that comes in over the MIDI In port back out so MIDI devices can be daisy chained together. MIDI Out can be used by the RetroCade to output MIDI data such as timing, change control's or notes.

Name

Function

Direction

Arduino Pin

Papilio Wing Pin

Papilio Pro Pin

Papilio One Pin

MIDI TX

MIDI Out Connector

Output

32

C0

P114

P91

MIDI RX

MIDI In Connector

Input

33

C1

P115

P92

Technical Details
The RetroCade MIDI implementation is closely patterned after the recommended MIDI circuit implementation provided by the MIDI Manufacturers Association. The only deviation from the recommended design is the use of a 3.3V power connection instead of 5V on the MIDI Out connector. This is necessary since the Papilio Pro uses 3.3V voltage levels instead of 5V levels.

MegaWing Sound

Since sound is the most important aspect of the RetroCade Synth we have gone all out with the audio section. Two top of the line 1/4" Neutrik audio jacks (datasheet) are used to ensure solid high quality audio connections. A low pass filter combined with a high speed Delta-Sigma DAC, as outlined in Xilinx App Note 154, allows high quality audio output to be realized. The high speed of the FPGA clock allows the FPGA to do the heavy lifting of the Digital to Analog conversion.

Name

Function

Direction

Arduino Pin

Papilio Wing Pin

Papilio Pro Pin

Papilio One Pin

A1-Left

Audio Jack 1 Left Channel

Output

17

B1

P97

P83

A1-Right

Audio Jack 1 Right Channel

Input

16

B0

P99

P85

A2-Left

Audio Jack 2 Left Channel

Output

18

B2

P92

P78

A2-Right

Audio Jack 2 Right Channel

Input

19

B3

P87

P71

MegaWing Character LCD

A 16x2 HD44780 compatible Character LCD is used to provide standalone control and feedback for the RetroCade. A standard backlight is provided for easy visibility in low light situations.

Name

Function

Direction

Arduino Pin

Papilio Wing Pin

Papilio Pro Pin

Papilio One Pin

LCD_Contrast

Contrast adjustment

Output

46

C14

P133

P16

LCD_RS

Register Select (RS). RS=0: Command, RS=1: Data

Output

26

B10

P62

P41

LCD_RW

Read/Write (R/W). R/W=0: Write, R/W=1: Read

Output

25

B9

P95

P54

LCD_E

Clock (Enable). Falling edge triggered

Output

24

B8

P74

P58

LCD_DB4

Bit 4

Output

23

B7

P78

P61

LCD_DB5

Bit 5

Output

22

B6

P80

P63

LCD_DB6

Bit 6

Output

21

B5

P82

P66

LCD_DB7

Bit 7

Output

20

B4

P84

P68

MegaWing Joystick

A really slick TPA511GLFS digital joystick is included to make navigating menu's a snap. It provides four directions and select in a compact fingertip controlled form factor.

Name

Function

Direction

Arduino Pin

Papilio Wing Pin

Papilio Pro Pin

Papilio One Pin

Joy_Left

Joystick Left

Input

28

B12

P57

P34

Joy_Down

Joystick Down

Input

29

B13

P55

P32

Joy_Select

Joystick Select

Input

31

B15

P47

P22

Joy_Right

Joystick Right

Input

27

B11

P59

P36

Joy_Up

Joystick Up

Input

30

B14

P50

P25

MegaWing MicroSD

The MicroSD (Secure Digital) socket expands the RetroCade with GigaBytes worth of storage space for your audio and configuration files. SD Fat libraries over the standard SPI interface allows files to be copied directly from your computer's filesystem onto an uSD card that can be read by the RetroCade.

Name

Function

Direction

Arduino Pin

Papilio Wing Pin

Papilio Pro Pin

Papilio One Pin

SD_DO

Data Out [MISO]

Input

42

C10

P126

P10

SD_DI

Data In [MOSI]

Output

44

C12

P131

P12

SD_SCK

Clock [SCLK]

Output

43

C11

P127

P11

SD_nCS

Card Select (Active Low)

Output

45

C13

P132

P15

MegaWing Analog Input

16 Analog inputs allow the RetroCade to be turned into a custom controller to implement your wildest controllerism ideas. The Analog header allows you to connect up to sixteen analog devices such as sliders, knobs, and analog joysticks. The header is even compatible with the Seeed Studio analog Grove devices when used with a Grove to Brick adapter. Easily add Grove Sliders, Grove Joysticks, or any other Analog Grove device.

The 16 analog channels are implemented with two ADC088S102CIMTX 8-bit, 8 Channel, SPI ADC's that are capable of sampling at speeds up to 1Msps.